The ability to achieve and sustain penile erection is a basic requirement for a male to have children and a happy marriage. The need to provide a controlled and sustained penile erection in impotent patients is well documented. Impotency may be due to a variety of causes, such as drugs, systemic disease, psychological, neurological, hormonal, arterial, venous or cavernous smooth muscle disorders. It has been estimated that more than ten million American males are impotent.
Along with the work of other researchers, applicants' extensive research on the anatomy, physiology, neuroanatomy, hemodynamics, pharmacology, radiology and ultrastructure of the penis has already revolutionized the diagnosis and treatment of impotence. For example, applicants' U.S. Pat. No. 4,585,005 discloses a system and method for augmenting penile erection electronically.
Hemodynamically, applicants' studies have shown that penile erection is a result of increased arterial blood flow, increased venous resistance and relaxation of the sinusoids within the corpora cavernosa. The vascular smooth muscle surrounding the sinusoids and the arteriolar wall is a primary consideration for controlling these events. In the flaccid state, the tonic discharge of the sympathetic nervous system maintains the muscles in a contracted state which allows minimal arterial flow into the penis.
Neurotransmittors (possibly a combination of acetylcholine, endothelial derived relaxing factor, vasoactive intestinal polypeptide and inhibition of alpha adrenergic tone) released as a result of sexual stimulation relaxes the vascular smooth muscles and results in large influx of arterial flow, expansion of the sinusoids and tumescence of the penis. Expansion of the sinusoids within a relatively confined space, limited by the tunica albuginea, compresses the subtunical draining venous channels which lie between the sinusoidal wall and the tunica albuginea before exiting as emissory veins. The nearly total closure of the draining venous system effectively contains most of the incoming blood within the sinusoids and results in engorgement, elongation and rigidity of the penis.
Applicants' studies have further shown that among the causes of erectile impotence, the final common pathway is the inability to initiate, store and maintain blood within the corpora cavernosa In non-vascular impotence, although the arterial, muscular and venous systems are intact, psychologic factors, nerve dysfunction or hormonal imbalance will result in a lack of neurotransmittors and inadequate erection In vascular impotence, most patients are still capable of realizing partial erection, but are unable to achieve coitus due to partial rigidity or inability to maintain the erection.
A more accurate diagnosis of various types of impotence are now possible due to the recent introduction of several innovative diagnostic tests The addition of rigiscan to nocturnal penile tumescence testing allows better assessment of penile rigidity during sleep and thus more accurate differentiation of psychogenic from organic impotence. The use of intracavernous injection of vasodilators, such as papaverine or prostaglandin E-1, allows office observation of a patient's erectile capability. When ultrasound and pulsed Doppler wave analysis is performed, before and after vasodilator injection, accurate functional evaluation of the penile arteries can be made. Pharmacologic cavernosometry and cavernosography can further assess the degree and location of venous incompetence. Several techniques of nerve conducting tests have also been developed for the evaluation of penile nerves and neurogenic impotence.
The treatment of erectile impotence has largely depended on sex therapy or psychotherapy, before the advent of implantable penile prosthesis. Various types of implantable prosthesis provide an effective tool for restoring the ability to achieve and maintain penile erection. However, the insertion of a foreign substance, whether of the inflatable or semirigid prosthesis type, invariably incites a scarring reaction and normally destroys substantial amounts of penile erectile tissues.
The recent introduction of intracavernous injection of pharmacologic agents, such as papaverine, papaverine with phentolamine, or prostaglandin E-1, has received wide attention. In non-vascular or minimal vasoular impotent patients, injection of these vasoactive substances induces erection, lasting for a variable period of time, e.g., from several minutes to several hours Two major complications have been observed priapism and fibrosis of the corpora cavernosa. If not promptly treated, priapism will result in extensive necrosis of the penile tissues and complete fibrosis of the corpora cavernosa. Long term injection of the papaverine can also induce extensive scarring of the penile erectile tissue.
Another modality that has been introduced recently is the vacuum suction device for penile erection The penis is placed within a suction device for several minutes until tumescence occurs. A tourniquet is then applied tightly and exteriorly at the base of the penis to restrict all venous outflow. The major disadvantage of this device is numbness and petechia of the penile skin after several minutes of tight proximal constriction.
None of the above systems or methods is ideal for all classes of impotent patients.